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><H1
><A
NAME="ECPG-SQL-CONNECT"
></A
>CONNECT</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN42953"
></A
><H2
>Name</H2
>CONNECT&nbsp;--&nbsp;establish a database connection</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN42956"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>CONNECT TO <TT
CLASS="REPLACEABLE"
><I
>connection_target</I
></TT
> [ AS <TT
CLASS="REPLACEABLE"
><I
>connection_name</I
></TT
> ] [ USER <TT
CLASS="REPLACEABLE"
><I
>connection_user_name</I
></TT
> ]
CONNECT TO DEFAULT
CONNECT <TT
CLASS="REPLACEABLE"
><I
>connection_user_name</I
></TT
>
DATABASE <TT
CLASS="REPLACEABLE"
><I
>connection_target</I
></TT
></PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN42963"
></A
><H2
>Description</H2
><P
>     The <TT
CLASS="COMMAND"
>CONNECT</TT
> command establishes a connection
     between the client and the PostgreSQL server.
    </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN42967"
></A
><H2
>Parameters</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="REPLACEABLE"
><I
>connection_target</I
></TT
></DT
><DD
><P
>        <TT
CLASS="REPLACEABLE"
><I
>connection_target</I
></TT
>
        specifies the target server of the connection on one of
        several forms.

        <P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
>[ <TT
CLASS="REPLACEABLE"
><I
>database_name</I
></TT
> ] [ <TT
CLASS="LITERAL"
>@</TT
><TT
CLASS="REPLACEABLE"
><I
>host</I
></TT
> ] [ <TT
CLASS="LITERAL"
>:</TT
><TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
> ]</DT
><DD
><P
>            Connect over TCP/IP
           </P
></DD
><DT
><TT
CLASS="LITERAL"
>unix:postgresql://</TT
><TT
CLASS="REPLACEABLE"
><I
>host</I
></TT
> [ <TT
CLASS="LITERAL"
>:</TT
><TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
> ] <TT
CLASS="LITERAL"
>/</TT
> [ <TT
CLASS="REPLACEABLE"
><I
>database_name</I
></TT
> ] [ <TT
CLASS="LITERAL"
>?</TT
><TT
CLASS="REPLACEABLE"
><I
>connection_option</I
></TT
> ]</DT
><DD
><P
>            Connect over Unix-domain sockets
           </P
></DD
><DT
><TT
CLASS="LITERAL"
>tcp:postgresql://</TT
><TT
CLASS="REPLACEABLE"
><I
>host</I
></TT
> [ <TT
CLASS="LITERAL"
>:</TT
><TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
> ] <TT
CLASS="LITERAL"
>/</TT
> [ <TT
CLASS="REPLACEABLE"
><I
>database_name</I
></TT
> ] [ <TT
CLASS="LITERAL"
>?</TT
><TT
CLASS="REPLACEABLE"
><I
>connection_option</I
></TT
> ]</DT
><DD
><P
>            Connect over TCP/IP
           </P
></DD
><DT
>SQL string constant</DT
><DD
><P
>            containing a value in one of the above forms
           </P
></DD
><DT
>host variable</DT
><DD
><P
>            host variable of type <TT
CLASS="TYPE"
>char[]</TT
>
            or <TT
CLASS="TYPE"
>VARCHAR[]</TT
> containing a value in one of the
            above forms
           </P
></DD
></DL
></DIV
><P>
       </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>connection_object</I
></TT
></DT
><DD
><P
>        An optional identifier for the connection, so that it can be
        referred to in other commands.  This can be an SQL identifier
        or a host variable.
       </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>connection_user</I
></TT
></DT
><DD
><P
>        The user name for the database connection.
       </P
><P
>        This parameter can also specify user name and password, using one the forms
        <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>user_name</I
></TT
>/<TT
CLASS="REPLACEABLE"
><I
>password</I
></TT
></TT
>,
        <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>user_name</I
></TT
> IDENTIFIED BY <TT
CLASS="REPLACEABLE"
><I
>password</I
></TT
></TT
>, or
        <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>user_name</I
></TT
> USING <TT
CLASS="REPLACEABLE"
><I
>password</I
></TT
></TT
>.
       </P
><P
>        User name and password can be SQL identifiers, string
        constants, or host variables.
       </P
></DD
><DT
><TT
CLASS="LITERAL"
>DEFAULT</TT
></DT
><DD
><P
>        Use all default connection parameters, as defined by libpq.
       </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN43046"
></A
><H2
>Examples</H2
><P
>     Here a several variants for specifying connection parameters:
</P><PRE
CLASS="PROGRAMLISTING"
>EXEC SQL CONNECT TO "connectdb" AS main;
EXEC SQL CONNECT TO "connectdb" AS second;
EXEC SQL CONNECT TO "unix:postgresql://200.46.204.71/connectdb" AS main USER connectuser;
EXEC SQL CONNECT TO "unix:postgresql://localhost/connectdb" AS main USER connectuser;
EXEC SQL CONNECT TO 'connectdb' AS main;
EXEC SQL CONNECT TO 'unix:postgresql://localhost/connectdb' AS main USER :user;
EXEC SQL CONNECT TO :db AS :id;
EXEC SQL CONNECT TO :db USER connectuser USING :pw;
EXEC SQL CONNECT TO @localhost AS main USER connectdb;
EXEC SQL CONNECT TO REGRESSDB1 as main;
EXEC SQL CONNECT TO AS main USER connectdb;
EXEC SQL CONNECT TO connectdb AS :id;
EXEC SQL CONNECT TO connectdb AS main USER connectuser/connectdb;
EXEC SQL CONNECT TO connectdb AS main;
EXEC SQL CONNECT TO connectdb@localhost AS main;
EXEC SQL CONNECT TO tcp:postgresql://localhost/ USER connectdb;
EXEC SQL CONNECT TO tcp:postgresql://localhost/connectdb USER connectuser IDENTIFIED BY connectpw;
EXEC SQL CONNECT TO tcp:postgresql://localhost:20/connectdb USER connectuser IDENTIFIED BY connectpw;
EXEC SQL CONNECT TO unix:postgresql://localhost/ AS main USER connectdb;
EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb AS main USER connectuser;
EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb USER connectuser IDENTIFIED BY "connectpw";
EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb USER connectuser USING "connectpw";
EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb?connect_timeout=14 USER connectuser;</PRE
><P>
    </P
><P
>     Here is an example program that illustrates the use of host
     variables to specify connection parameters:
</P><PRE
CLASS="PROGRAMLISTING"
>int
main(void)
{
EXEC SQL BEGIN DECLARE SECTION;
    char *dbname     = "testdb";    /* database name */
    char *user       = "testuser";  /* connection user name */
    char *connection = "tcp:postgresql://localhost:5432/testdb";
                                    /* connection string */
    char ver[256];                  /* buffer to store the version string */
EXEC SQL END DECLARE SECTION;

    ECPGdebug(1, stderr);

    EXEC SQL CONNECT TO :dbname USER :user;
    EXEC SQL SELECT version() INTO :ver;
    EXEC SQL DISCONNECT;

    printf("version: %s\n", ver);

    EXEC SQL CONNECT TO :connection USER :user;
    EXEC SQL SELECT version() INTO :ver;
    EXEC SQL DISCONNECT;

    printf("version: %s\n", ver);

    return 0;
}</PRE
><P>
    </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN43052"
></A
><H2
>Compatibility</H2
><P
>     <TT
CLASS="COMMAND"
>CONNECT</TT
> is specified in the SQL standard, but
     the format of the connection parameters is
     implementation-specific.
    </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN43056"
></A
><H2
>See Also</H2
><A
HREF="ecpg-sql-disconnect.html"
>DISCONNECT</A
>, <A
HREF="ecpg-sql-set-connection.html"
>SET CONNECTION</A
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